JPH01315174A - Semiconductor light-emitting device - Google Patents

Abstract

PURPOSE:To obtain short wave length emission of green-yellow by growing a GaInP system mixed crystal on a group III-V board as a first layer by a yo-yo solute supply method or an Sn solvent method and further laminating the GaInP system mixed crystal as a second layer thereon. CONSTITUTION:A GaInP layer 12 which is a first layer of a GaInP mixed crystal is formed on a GaP board 11 by a yo-yo solute supply method. Next multilayers which have double hetero-junction as a second layer of a GaInP layer system mixed crystal on the GaInP layer 12, namely, an AlGaInP clad layer 13, a GaInP active layer 14 and an AlGaInP clad layer 15 are formed by vapor phase epitaxy by the use of an MOVPE (metal organic vapor phase epitaxial growth method), an MBE (molecular beam epitaxial growth method) and the like in order. Thereby short wave emission of green-yellow can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a substrate made of ■-V group elements (hereinafter referred to as m-v group substrate) and ■ containing at least Ga, In, and P elements. The present invention relates to semiconductor light emitting devices such as light emitting diodes (LEDs) and semiconductor lasers (LDs) that are composed of GaInP-based mixed crystals of the -■ group mixed crystals.

[Prior art/problems to be solved by the invention] GaInP based on GaInP, which is a ■-V group ternary alloy compound semiconductor material, is a compound semiconductor material of ■-■ group compound semiconductors excluding nitrides. It has a direct transition bandgap with a large crystal content and is the most advantageous material for constructing light-emitting devices that emit not only red wavelength light but also green to yellow light.
Currently used as a material for red LEDs and LDs.

Therefore, the ■-■ group substrate 200 as shown in FIG.
If a light-emitting element having a structure consisting of a GaInP-based first layer 210 containing GaInP as a main component and a GaInP-based second layer 220 containing GaInP as a main component, which is a buffer layer for child matching, can produce green to Yellow short wavelength light emission can be achieved.

Various attempts have been made to obtain a light emitting device having the structure shown in FIG.
A GaAs substrate is used as the group V substrate 200, and the GaAs
There has been an attempt to deposit a GaInP-based second layer 220 on the substrate by MOVPE (metal-organic vapor phase epitaxial growth) (in this case, the second layer 210 for lattice matching is deposited on the substrate).
is not necessary).

However, in the above attempts, the second layer 220 and GaAs
Due to constraints on lattice matching with GaInP, red light is emitted when the light emitting region is formed of GaInP. In order to shorten the wavelength of green to yellow in this system, the light emitting region should be made of AlGar containing Al.
The light emitting device has low reliability and performance due to the presence of A1, which must be formed of nP and is easily oxidized.

Furthermore, in the prior art, the ■-■ group substrate 200 is
An aAs or GaP substrate is used, and a GaPAs growth layer (layer 2 in FIG. 10) for lattice matching is formed on the substrate.
10) is used as a substrate, and 28
GaIn on a substrate with a GaPAs growth layer
When the P-based second layer 220 is grown under lattice matching conditions, yellow to green light can be emitted using AlGarnP with a low Al content or GaInP containing no Al as a light emitting region.

However, although the GaPAs substrate is usually produced by vapor phase growth, it has a unique crosshatch pattern surface morphology, and even if multiple layers are formed on it, it is difficult to improve the surface morphology and a flat interface cannot be obtained. do not have. In addition, there are many misfit dislocations with high density, and when LEDs and LDs are manufactured, their performance and reliability are significantly lowered.

Therefore, the object of the present invention is to form a GaInP-based mixed crystal layer containing a GaInP-based mixed crystal and a GaInP-based substrate as shown in FIG. 10.
An object of the present invention is to provide a semiconductor light emitting device which is a semiconductor having a layer and a second layer and can emit short wavelength light from green to yellow.

[Means to solve the problem]

In order to achieve the above object, the semiconductor light emitting device of the present invention includes a substrate made of a ■-V group element, and a substrate made of a
A third layer mainly composed of GaInP formed using an o-yo solute supply method or an Sn solvent method, and a MO layer formed on the first layer.
It is characterized by comprising a second layer mainly composed of GaInP formed using a method selected from VPE, MBE, and LPE.

In the light emitting device of the present invention, the yo-yo solute supply method or the S
m-v group (GaP, GaAs) by n-solvent method.

Ga InP-based (GalnP, etc.) substrate
AlGaInP.

Ga [nPAs, etc.) mixed crystal can be grown as the second layer, and furthermore, conventionally known MOVPE and MBE.

GaI on the first layer by a method selected from
By laminating the nP-based mixed crystal as a second layer (which often acts as a cladding layer, an active layer, etc.), short wavelength light emission in the range of green to yellow can be obtained.

Both the yo-yo solute supply method and the Sn solvent method described above are methods of forming a solid solution layer containing GaEnP as a main component on a semiconductor substrate by LPH.

Details of both will be described later. Regarding the Sn solvent method, as a result of using the EI Sn solvent method, the amount of Sn doped into the second layer of the GaInP mixed crystal is xQlff~10
It is about '''/d, preferably about 10.'''/cd.

Methods for growing a second GaInP-based mixed crystal layer on a GaInP-based first layer formed by a yo-yo solute supply method or an Sn solvent method include conventionally known methods such as MOVPE (metal-organic vapor phase epitaxial growth) and MBE ( A method selected from molecular beam epitaxial growth method) and LPE (liquid phase epitaxial growth method) is used.

In the present invention, the group ■-v substrate includes at least one group III element and at least one V element in the periodic table.
There is no particular limitation as long as it is a compound semiconductor crystal substrate made of group elements, but in particular GaP substrates, GaAs substrates, and InP
GaIn layered on a 0m-v group substrate
The first layer and the second layer of P-based mixed crystal are made of at least Ga-In.
- Green color from the obtained light-emitting device containing three elements of P
There is no particular restriction as long as a yellow short wavelength light emitting device can be obtained; for example, GaInP, AlGaInP, Ga
Examples include InPAs.

〔Example〕

EMBODIMENT OF THE INVENTION Hereinafter, the semiconductor light emitting device of this invention will be explained in detail based on an Example.

The structure of a light-emitting device in which a GaInP-based layer was formed on a ■-V group substrate using the y o y O7g material supply method was first described.
2 and 2, and FIGS. 3 and 4 show the structure of a light emitting device in which a GaInP-based layer is formed on a ■-■ group substrate using the Sni medium method.

First, Figure 1 shows a GaP substrate 1 on a substrate made of ■-V group elements.
This light-emitting device is a basic structural diagram of a double heterostructure using GaInP layer 12, which is a GaInP-based mixed crystal layer 12, formed on a GaP substrate 11 by a yo-yo solute supply method. The second layer of GaInP-based mixed crystal is a multilayer with a double heterojunction, that is, Al
GaInP cladding layer 13, GaInP (or A
A (GaInP, GaInPAs) active layer 14 and a (GaInPn) active layer 15 are epitaxially grown in this order.

FIG. 2 shows a single heterostructure light emitting device using a GaP substrate 21.
An InP layer 22 is formed by a yo-yo solute supply method,
A multilayer with a single heterojunction as a second layer on the GalnP layer 22, that is, GaInP (or AlG
aInP, GaInPAs) active layer 23 and Al
GaInP cladding layers 24 are epitaxially grown in sequence. In the present invention, since there is generally a large lattice constant mismatch between the substrate and the second layer, in order to reduce the effects of strain and dislocation caused by this, , No.-
It is better to make the thickness of the layer, that is, the GalnP layer, as thick as possible.

In the light emitting device shown in FIGS. 1 and 2 above, GaP
Y used to grow the second layer of GaInP on the substrate
The o-yo solute supply method is carried out as follows.

In the method using the yo-yoR quality supply method shown in FIG.
VPE and MOVP are mounted on a normal GaP substrate as the substrate 71.
A GaInP mixed crystal layer having a desired mixed crystal composition may be grown directly by E, MBE, or LPE.

As shown in FIG. 5(a), when a GaP substrate 71 is placed on the upper side, for example, when it is desired to obtain a green LED, etc., a GalnP alloy 72 having a composition of 0.73 in mole fraction of GaP is used.
Place at the bottom. The GaP substrate 71 used has an area lX
1d, crystal plane orientation (100), (ill) B or (111) A, carrier concentration io” ~to/c
It is d.

A substrate having these plane orientations may be a just substrate, or may have an off-angle of about 0.5 to 10 degrees, preferably an off-angle of about 1 to 5 degrees.

At this time, it goes without saying that the surface of the GaP substrate is polished and the surface is sufficiently cleaned with an appropriate etching solution.This GalnP alloy is obtained by the following manufacturing method. One is to grind GaP% InP crystals into powder, prepare the mole fraction of GaP to be 0.73, and then heat the powder at about 1070'C in a vacuum-sealed quartz ampoule.
A method of sintering for 4 hours, or a molar ratio of InP:Ga
P = 27: The 73 raw materials are melted at 1450'C or higher using a high-pressure furnace that can prevent each from disassociating, and the composition of this rnP-GaP JiJ4Ql binary melt (Pseudobinary 5 solution) is made sufficiently uniform. It can be obtained by quenching and solidifying it. The solution used is 700-1000°
C1 Preferably at 750-850°C, the molar fraction of GaP is 0.75-1.0, preferably 0.8-0.
It is adjusted to precipitate a solid solution having a composition of 95.

Specifically, for example, 'r,, (810'c, Fig. 5 (
In order to precipitate a solid solution having a composition with a GaP mole fraction of 0.84 in [see b)], a solution in which 9.43 cm of InP and 92.48 cm of GaP are dissolved in 5 g of In is used. A solution with better uniformity is, for example, one in which GaP and InP crystals are heated at 100''C in an In solvent.
It can be obtained by dissolving the mixture in a water bottle, stirring it for about 24 hours, and then rapidly cooling it. As a result, the GaP substrate 71, Ga
An lnP alloy 72 and a solution 73 are prepared. In-Ga-P corresponding to a solid solution with a molar fraction of GaP of 0.84
Raise the temperature of the solution to a temperature higher than 810℃ (810℃+
ΔT), and cooling is started at a cooling rate of 0.05 to b, which is the cooling rate used in normal LPE. Of course, these processes are performed in a high purity inert gas or H2 gas atmosphere. When the temperature reached Th (805°C), that is, at time t□ in Figure 5 (4), the solution was transferred to the GaP substrate 7.
1 and GalnP alloy 72. The state is shown in FIG. 5(a), where the thickness of the solution is about 500 mm. g indicates the direction of gravity, and in order to obtain growth with good flatness, it is important that the GaP substrate 71 and the GalnP alloy 72 are placed parallel and horizontally. When the solution is cooled to TL (790°C) at the above cooling rate, the solution becomes supersaturated, but due to the difference in specific gravity, GaIn mainly forms on the GaP substrate.
Growth of P occurs.

The mixed crystal composition is 0.05 to 5 degrees (/win, preferably 0. The temperature is raised to T at a rate of 2 to 1°C/sin.At this time, the solution gradually becomes unsaturated, but due to the effect of the difference in specific gravity, the GalnP alloy 72 at the bottom is mainly dissolved.This GalnP alloy The composition of 72 is GaP mole fraction of 0.7
3, the solution shifts somewhat to the fP side at time 1. □
This cycle is repeated after holding at T for 10 minutes from ts+ to No change in the composition of the precipitated solid solution occurs. The state at that time is shown in FIG. 5), where 74 is a GaInP relaxation layer contained in the first layer, which is composed of multiple layers in which the components are changed in stages. Thereafter, by repeating several temperature cycles, a third layer of GalnP having a desired thickness with a constant mixed crystal composition of 0.73 in mole fraction of GaP is formed in accordance with the number of repetitions of the temperature cycles. can be grown. Figure 5 (
C) shows this state. 75 indicates the target mixed crystal composition, that is, a GaInP mixed crystal layer having a constant composition with a GaP molar fraction of 0.73. When the growth is finished, either slide the GaP substrate 71 and separate it from the solution, or remove the GaP substrate 71 from the solution.
It is important to rotate the P substrate 71, the raw material GaInP alloy 72, and the solution 73 to reverse the vertical relationship between the GaP substrate 71 and the GaTnP raw material alloy 72 to prevent excessive precipitation from occurring on the GaP substrate during cooling. From 0 or more,
In this temperature process, each time the temperature cycle is repeated, the GaP mole fraction decreases by about 0.012.
The P $1 sum layer 74 grows stepwise, and after 10 [periods], the GaInP mixed crystal composition is constant at 0.73 in mole fraction of GaP and the desired thickness corresponds to the number of temperature cycles. This shows that the crystal layer 75 can grow. In this embodiment, the -th layer consists of the above layer 74 and layer 75.

Next, another example for forming the first layer using the yo-yo solute supply method will be described. In this embodiment, a -th layer that does not include the formation of the relaxation layer 74 is formed on the semiconductor substrate.

So far Y, 0hki, 1. Asano+ and
r, Akasaki et al., M Magazine J, Cryst,
Growth, vol, 24/25+ p224(1
974), GaP (100) and (111) B
On the substrate, Gal with a GaP mole fraction ranging from 0.5 to 0.9 is deposited by Chloride VPE.
They report that they were able to grow an nP layer. Also, S, K
ondo, S., Matsumoto.

and H, Nagai et al., in the journal App1. P
hys, Lett,, vol.

53, No, 4. p25 (July, 1988
), GaAs was first grown on a Si substrate by MOVPE, followed by MO-Chlo-ride VPE.
reported that GaInP was grown at a mole fraction of GaP of 0.5. However, for LPH, J. NiN15hiza and S. Yosh
ida et al., J.Cryst, Growth, v.
ol-78+ p 274-278+ (1986),
When GaInP with a mole fraction of GaP of 0.7 is grown using GaP (111) B as a substrate, the grown layer does not become layered but columnar (Ga, 71na,
sP, epitaxial layer with
5hape coluwar grown
onGaP 5 substrate). On the other hand, the present inventors have discovered that a layered GaInP mixed crystal layer having a predetermined composition can be grown on a GaP substrate using LPH as well, as described below.

Of course, if a crystal in which a GalnP layer is grown on GaP is used as the substrate 71, it is possible to grow the GalnP layer 75 having the desired mixed crystal composition directly on the substrate without providing the stepped composition gradient layer 74. Needless to say.

Now, a method of growing a GalnP layer of a desired composition directly on a GaP substrate by LPH will be described with reference to the slide boat shown in FIG.

In the figure, 113', 113' are flanges, 114.
114' is a pulp for atmospheric gas, 116 is a quartz tube, 11
7 is an electric furnace, 121 is a growth solution introduction hole, 122 is an excess solution outlet hole, and 123 is an excess solution receiving tray.

Here, the GaP (111) B plane is used as a seed crystal substrate (Ili-V group substrate), and In1-++ is deposited on it.
The case of growing Ga and IP will be explained as an example. First, GaP (111) B purified by a known method
The planar seed crystal substrate 101 is placed in a suitable slide boat, for example, on the upper side of the boat 120, and the In1-x Gas P raw material alloy 102 having the desired mixed crystal composition is placed on the lower side.

As described later, GaP may be used as this raw material alloy, and the composition of the growth solution 103 is adjusted to precipitate a solid solution with the desired composition and to have an appropriate degree of supercooling at the growth start temperature. It is.

After these materials are loaded into the boat 120, high purity hydrogen gas is flowed into the growth system to sufficiently clean the atmosphere. Then, the temperature of this growth system is raised to a temperature somewhat higher than the equilibrium temperature of the solution 103' as shown in FIG. become

In this example, in order to obtain a green-emitting LED etc. and to equilibrate the solution 103' at 820°C
The atomic ratio of ' is approximately In:Ga:P-95:1.5:
Since the temperature was adjusted to 3.5, the homogenization temperature of the solution was 850°C.
And so. Thereafter, the solution is cooled to its equilibrium temperature T, .

This temperature may be slightly higher than the equilibrium temperature.
This temperature is held constant to allow the solution to reach a steady state. Specifically, In-G was kept at a constant temperature of 820-825°C for 30 minutes to 2 hours and charged into a cylinder.
Ensure that the a-P solution 103' is sufficiently and uniformly mixed. Then, by operating the piston 119, the solution is injected into the gap between the seed crystal 101 and the raw material alloy 102 for 30 minutes to 1 hour.
By keeping the temperature constant for a period of time, the seed crystal 101 and the molten i'! ! 103 to achieve sufficient thermal equilibrium at the solid-liquid interface. Thereafter, slow cooling is performed at an appropriate cooling rate, for example, 0.1 to 0.5°C/min, to form nuclei on the seed crystal substrate, and further two-dimensional growth is performed to form the desired mixture on the GaP substrate. Crystal composition, e.g. I
I;aa, tslno, ! ? An initial growth layer of p can be obtained.

A specific example of growth is 0.823°C to 818°C.
By cooling at a rate of 5 °C/min and then slowly cooling at 0.2 °C/min from 818 to 790 °C, an initial growth layer of Gao, tlno, and 3P with a thickness of 3 to 5 pm was formed on the GaP substrate. I was able to grow it. This gradual cooling is effective for promoting two-dimensional growth. A temperature program of 0 or more is just one example, and it goes without saying that an initial growth layer can be obtained using other methods.

After forming the initial growth layer in this way, the temperature is 790°C (T
In step 1), the temperature is maintained for about 20 minutes, and then a process similar to the temperature process starting from time t□ in FIG. 5(a) begins, for example. Specifically, for example, T.

±790°C, Th-8 at 0.3-0.8°C/min
After raising the temperature to 0.05°C and holding the temperature constant for 20 to 30 minutes, slowly cooling it to 790°C at a rate of 0.3 to 1'C/min, and then keeping the temperature constant for 20 minutes to complete one cycle. The temperature process was repeated. Then, after 30 cycles of growth, a good gas with a thickness of 200 mm, 71ne
, , a p-layer could be formed.

Although the case where the GaP (111) B plane of the seed crystal substrate is used has been described above, the present invention can also be practiced with other plane orientations, such as the (100) plane.

In addition, as the raw material alloy, a target GaInP mixed crystal composition may be used. For example, even when GaP is used as the raw material alloy, by appropriately setting the temperature raising process and the temperature lowering process, the raw material alloy can be used in each cycle. It is possible to grow a GaInP mixed crystal having a desired composition by matching the amount of GaP dissolved in the solution 103 with the amount of GaP0 contained in the growing GaInP mixed crystal.

In-Ga-P in these yo-yo solute supply methods
In a solution, the solute is always subjected to an upward force due to the difference in specific gravity, so growth on the GalnP alloy side can be almost ignored, and most of the growth occurs on the upper GaP substrate. Then, after holding the temperature at a constant temperature for a certain period of time, the temperature is raised at a constant heating rate to the temperature at which growth starts. At that time, the solution gradually becomes unsaturated, but the solution that has reached almost saturation due to dissolution from the Ga'lnP alloy is quickly transported to the vicinity of the upper GaP substrate due to the difference in specific gravity, so that the solution near the GaP substrate remains saturated even at elevated temperatures. is maintained, and there is no meltback from the GaP substrate.After the temperature is maintained at a constant temperature for a certain period of time, cooling is started again. By repeating this temperature cycle, it becomes possible to grow a GaInP mixed crystal on a GaP substrate using a Ga■nP alloy as a raw material.

In other words, the yo-yo solute supply method utilizes the fact that the gravity field and the specific gravity of the solution depend on the concentration of the solute contained in the solution, and it was named so because it periodically raises and lowers the temperature. .

Next, FIG. 3 shows a light emitting device with a double heterostructure using a GaAs substrate 31 as a substrate made of a -V group element. - layer of Sn-doped GaInP
A multilayer layer 32 having a double heterojunction, that is, an AlGaInP cladding layer 33 and a GaInP cladding layer 33, is formed as a second layer of a1nP mixed crystal on top of the Sn-doped GaInP layer 3.
InP (or GaInP, GaInPA
s) An active layer 34 and an AlGaInP cladding layer 35 are epitaxially grown in this order.

FIG. 4 shows a single heterostructure light emitting device using a GaAs substrate 41.
A Sn-doped GaInP layer 42 as a second layer is formed on the Sn-doped GaInP layer 42, and a multilayer having a single heterojunction, that is, a GaInP layer, is formed as a second layer on the Sn-doped GaInP layer 42.
(or ^IGaInP 5GalnPAs) An active layer 43 and an AlGaInP cladding layer 44 are epitaxially grown in this order.

Sni used for growing the GaInP-based layer on the GaAs substrate in the light emitting devices shown in FIGS. 3 and 4 above.
In the medium method, for example, a solution containing Ga and InP or GaP and InP is prepared using Sn as a solvent, and this solution can be grown on a substrate by known means. At this time, InP and GaP or Ga and I added to the Sn solvent
In order to obtain yellow to green light emission, the amount of nP should be determined so that the mixed crystal composition of each GaInP growth layer precipitated from the solution is Ga.
The mole fraction of P should be in the range of 0.55 to 0.75, but if the growth solution is mixed with Ga and I in Sn solvent,
When fabricated by adding nP, meltback of the GaAs substrate occurs, so InP is added to the 5nfJ medium.
It is more preferable to grow the GalnP layer using a solution containing GaP and GaP.

The precipitation of GaInP crystals is performed, for example, as follows. That is, Sn is used as a metal solvent, GaP and InP are added thereto, and the mixture is heated to a GaInP crystal growth temperature to produce a metal solution containing the four components of 5n-In-P-Ga. At this time, the amounts of each component are adjusted so that a solid solution with a desired composition or a solid solution close to the desired composition is precipitated. Further, at this time, in the solution, the total number of atoms of In and Ga, which are group II elements, is dissolved in a ratio equal to the number of atoms of P, which is a group II element, that is, in a stoichiometric ratio. Ga containing 0.55 to 0.75 mole fraction of GaP necessary to obtain light emission in the yellow to green band
To grow InP mixed crystal, InP dissolved in Sn solvent is used.
The ratio of P and GaP is 1 in terms of the total molar amount of rnP and GaP.
00%, GaP may be selected at an appropriate value within the range of 3 to 40 mol%.

The solution prepared in this way was heated with G at a temperature slightly supersaturated.
GaI in solution can be cooled while in contact with the aAs seed crystal substrate, or by creating a temperature gradient so that the temperature of the seed crystal substrate is lower than the saturation temperature of the solution.
The nP becomes supersaturated and is deposited on the GaAs seed crystal substrate to grow GaInP crystals.

The GaInP crystal obtained in this way has few lattice defects.This is because by using Sn as a solvent and dissolving InP and GaP in it, the solute in the Sn solution is maintained at a stoichiometric ratio. That is, this is based on the result that the Group Ⅰ element and the Group V element are contained in an atomic ratio of 1:1 or in a stoichiometric ratio. This is due to the following two reasons.

The first reason is that by using this growth solution, Ga
The point is that it is now possible to prevent the As substrate from melting. This is because even if GaAs is dissolved in this 5ntI solution, the chemical equivalence ratio of Group I and Group V will not change, and the dissolution of a trace amount of GaAs in this solution will cause GaAs to dissolve in the solution.
This is to rapidly lower the solubility of nP. That is, Ga
If the As substrate tries to dissolve, this will cause precipitation of GaInP, and as a result, dissolution of GaAs can be prevented. On the other hand, GaI
The In--Ga--P ternary solution used for the growth of nP is a solution with a non-stoichiometric ratio, and the solution composition is quite biased toward the group (I) element excess side.

Therefore, even if the In-Ga-P ternary solution is a saturated solution at the growth temperature, GaAs will dissolve when the ternary solution comes into contact with GaAs.

The second reason is that the lattice constant mismatch that exists between the GaAs substrate and the GaInP growth layer can be alleviated by using a growth solution in which InP and GaP are dissolved in a Sn solvent. The relaxation mechanism is not clear at present, but the following two things can be considered.

In order to describe the relaxation mechanism, lattice mismatch will first be explained based on the graph shown in FIG. I
The lattice constant of nP is 5.8688 and that of GaP is 5.4505. Therefore, when InP and GaP are mixed to form a GaInP mixed crystal, the lattice constant takes a value between the respective lattice constants of InP and GaP depending on the composition of the mixed crystal. On the other hand, the lattice constant of GaAs used as a substrate is 5.6534, and when the mixed crystal composition of GaInP is x -0.51, where the mole fraction of GaP contained in the mixed crystal is Matches crystal. However, as is clear from Fig. 7, the important mixed crystal composition range for visible light emitting materials, that is, x > 0.51.
In the range of , the lattice constant of the GaInP mixed crystal becomes smaller than that of GaAs, resulting in lattice mismatch.

The first possible mechanism for alleviating this lattice mismatch is the effect of adding Sn impurities. This will be explained in detail. ■- such as InP, GaP, XGaAs, etc.
Both the V group compound and the GarnP mixed crystal have a zincblende crystal structure. According to chemical bonding theory, the lattice constant depends on the interatomic distance between the group ■ atoms and the group ■ atoms, and the interatomic distance is determined by the tetrahedral covalent bond radius ( (hereinafter abbreviated as covalent radius) is known to almost match the sum of Second revised edition (Kyoritsu Shuppansha, 4th revised edition published on August 10, 1960)
According to page 24, table 7-13, P: 1.10 people, A
s: 1.18 people, Ga: 1.26 people, In s 1
．． 44 people, Sn: 1.40 people. Therefore, the interatomic distance is fnP: 2.54, GaP: 2.36
People, GaAs: 2.44 people. In the GaInP mixed crystal, In and Ga are mixed on the group II sublattice, so the weighted average value of the covalent bond radius of Ga and In and P, taking into account the composition ratio of the mixed crystal, are The sum with the covalent bond radius becomes the average interatomic distance for this mixed crystal.

On the other hand, Sn used as a solvent is a Group 1 element, and can be substituted with atoms on either the sublattice of the Group 2-2 compound on the ■ plate side or the V plate side as a so-called amphoteric impurity. Therefore, for example, when Sn replaces Ga on the Ga sublattice of GaP, the interatomic distance increases from 2.36 in GaP to 2.50, which is the sum of the respective covalent bond radii of Sn and P. Further, when P and Sn are substituted on the P sublattice, the interatomic distance becomes 2.66 people. Therefore, when Sn is added to GaP, as the interatomic distance increases, the GaP
The lattice constant of increases. When Sn is added to InP, the covalent bond radius of Sn is 1.40, and the value of In is 1.4.
Since Sn is slightly smaller than 4, I
When substituted with n, the interatomic distance decreases slightly. However, when Sn replaces P on the P sublattice, the covalent bond radius of Sn is considerably larger than that of P, so
The interatomic distance increases significantly. Therefore, even in the case of InP, the lattice constant increases with the addition of Sn.
Since this also holds true for GaInP, which is a mixed crystal of nP and GaP, the lattice constant of GaInP also increases by adding Sn.

It is understood that the lattice constant of the GaInP mixed crystal increases by adding Sn to the GaInP mixed crystal in this way.
A description will be given of how the lattice mismatch that exists between the s-substrate and the GaInP growth layer is alleviated. As mentioned above, the target GaInP mixed crystal has a mixed crystal composition x
>0.51, in which case the lattice constant of the GarnP mixed crystal becomes smaller than that of GaAs. Therefore, when GaInP having such a mixed crystal composition is grown on a GaAs substrate, strain occurs at the interface between the two due to lattice mismatch. However, the Sn present in the growth solution is automatically added to the GaInP to minimize the interfacial energy at this interface;
The lattice constant of GaInP is increased to reduce this strain and alleviate the lattice mismatch. GaIn
Since the strain decreases as the growth of P progresses, the amount of Sn added also decreases and reaches a steady value. In other words, the initially grown GalnP layer acts as a buffer layer with a lattice constant gradient due to the addition of Sn, and is thought to alleviate the lattice mismatch between the GaAs substrate and the GaInP mixed crystal layer of a given composition. It will be done.

The following is considered as a second mechanism for alleviating the lattice mismatch between the GaAs substrate and the GaInP growth layer obtained by adding Sn.

First, due to the impurity effect of Sn in the early stage of growth, G
Countless G particles with the same orientation as the GaAs substrate are deposited onto the aAs substrate.
At the zeroth order of growth of aInP island-like microcrystals, it becomes a nucleus, promoting lateral growth and expanding the island.

Eventually, the islands are connected to form a single crystal GaInP growth layer. After the GaInP layer is formed in this way, the ralnP layer is subsequently grown to obtain an epitaxially grown layer of a predetermined thickness. Lattice mismatch dislocations due to lattice constant mismatch occur between the GaAs substrate and the G
The resulting Ga
The InP growth layer has high quality.

As described above, it is believed that a GaInP growth layer of good quality can be obtained as a result of the lattice mismatch being alleviated by at least one of the first mechanism and the second mechanism.

After forming the GaInP-based second layer on the m-v group substrate as described above, the GaInP-based second layer may be formed by an optimal method selected from MOVPE and MBE%LPE.

In addition to the usual method, the LPE may be a yo-yo solute supply method that is used for forming the second layer.
In that case, the solution 103' shown in FIG.
A solution 103' having the same composition but a different conductivity type is separately prepared and used in place of the solution 103' at an appropriate stage of the temperature process shown in FIG. 5 (6) to form a second layer of the desired thickness. It is good to form.

In the present invention, a pn junction may be formed at the interface between the first layer and the second layer, or a double heterojunction or a single heterojunction may be formed in the second layer. for example,
AlGaInP cladding layer 13 as the second layer, GaIn
The P active layer 14 and the AlGaInP cladding layer 15 are made of Ga.
By sequentially epitaxially growing the lnP layer 12, a semiconductor light emitting device in which the second layer shown in FIG. 1 has a multilayer double heterostructure is manufactured.

In particular, a semiconductor light emitting device with a Peter structure has either a double heterojunction or a single heterojunction structure.
Luminous efficiency is higher than that of homojunction, and LED and L
It is most suitable for D. A pn junction may be formed at the Peter junction to form a surface emitting element, or a normal LD shape may be used.

In addition, by selectively diffusing dopants that have different conductivity types,
A light emitting region may be formed by a diffusion region and a GaInP active layer to form an LED or LD. In this case, the light emitting region becomes substantially narrow, improving current injection efficiency to the light emitting region, increasing luminance, and increasing speed. It is convenient because modulation can be obtained, and as a diffusion dopant, 5S is used as a donor.
Go, Be for acceptors such as Si, Te5Se, etc.
Examples include 5Cd, Mg, and Zn.

For example, when manufacturing a green LED in the double-hetero structure light emitting device using the GaP substrate shown in FIG. 1, electrodes El and E2 are provided as shown in FIG. Good structure similar to brightness LED (
, the band gap of the GaInP active layer 14 is 2.23e.
The bandgap of the AlGaInP cladding layer 13.15 may be set to 2.4 eV.

Furthermore, as shown in FIG. 9, based on the double heterostructure of FIG. Donor (acceptor for n-type) is diffused into the light emitting region A by the diffusion region DR and the GaInP active layer.
R may be formed, and the p-side electrode material and n-side electrode materials E1 and E2 may be provided by means such as vacuum evaporation. Light may be extracted from the end face or from the surface direction. In order to manufacture this, the striped active region may be formed into a resonator structure by further folding the material.

In particular, the light emitting device with the structure shown in FIG. 8 has a double heterojunction, and the light emitting device with the structure shown in FIG. It can be brightened and applied to a wide variety of applications.

Furthermore, the LD with the structure shown in FIG.
AlGaInP, GaInPAs) have the largest direct transition bandgap and are most advantageous for shortening wavelengths. It is a useful device that holds the key to improving the performance of optical information processing systems, such as increasing the density of disks and increasing the speed of laser printers.In addition, green to yellow visible light LDs are small and lightweight devices that emit visible coherent light. As a light source, it has the potential for new applications not found in conventional LDs that oscillate in the infrared region.

In addition, in the embodiment of the semiconductor light emitting device of the present invention, additional effects as described below can be obtained.

■-V group substrate When using a GaPa board in particular,
GaP and the -th layer emit light (green to green) of this semiconductor light emitting device.
Since it is transparent to yellow), it not only improves light extraction efficiency, but also allows emission to be extracted from the substrate side, making it possible to use a junction down structure that is advantageous for heat dissipation. Furthermore, light can be emitted in any direction by providing a reflector made of SiQ□ or by preventing reflection in the light extraction direction, so there is a great degree of freedom in designing the light emitting element.

Furthermore, since the GaP substrate has excellent heat dissipation properties, it becomes possible to efficiently dissipate heat generated in the active layer.

When forming a Sn-doped GaInP layer on the GaAs substrate by the Sn solvent method using a GaAs substrate as a group III-III substrate, a GaInP active layer of good quality crystal or a GaInP
An As active layer can be grown.

In either case of GaP substrate or GaAs substrate, A
Ga In that does not contain L or has a low Al content
By growing the P active layer, it is difficult for the device to deteriorate due to Al, and it is possible to provide a device with excellent stability and reliability. In particular, when used as an LD, high stability and high reliability are guaranteed.

[Effects of the Invention] Since the semiconductor light emitting device of the present invention is constructed as described above, the semiconductor light emitting device of the present invention has a
Green to yellow short wavelength light emission with a structure consisting of a 1nP mixed crystal first layer and a GaInP mixed crystal second layer is obtained.

As shown in the examples, in a semiconductor light emitting device using either a GaP substrate or a GaAs substrate, a p-n junction is formed by dopant control during crystal growth or by diffusion, By providing a p-side electrode and an n-side electrode, an LED with wavelengths in the green to yellow band can be easily obtained.

Further, by forming a resonator by folding the constituent materials as shown in FIG. 9, for example, a visible light LD having a short wavelength in the green to yellow band can be easily obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a light emitting element formed by the yo-yo solute supply method in the semiconductor light emitting device of the present invention, and FIG.
FIG. 3 is a cross-sectional view showing another example of a light-emitting element formed by the Sn solvent method in the semiconductor light-emitting device of the present invention; FIG. 5(a) to (e) are cross-sectional views showing another example of a light emitting element formed by the Sn solvent method in a semiconductor light emitting device. Figure 6 is a diagram for explaining the yo-yo solute supply method, which is a manufacturing method for forming a GaInP layer. A schematic cross-sectional view showing an example of a slide boat to be used. FIG. 7 is a schematic cross-sectional view showing an example of a slide boat to be used.
A graph showing the relationship between the composition ratio of GaP to GaInP mixed crystal and the lattice constant of the GaInP mixed crystal corresponding to that composition when forming GaInP mixed crystal by a solvent method. Figure 8 is the structure of Figure 1. FIG. 9 is a sectional view of an example of the semiconductor light emitting device of the present invention using the structure of FIG. 1 or 3, and FIG. Green color consisting of a group V substrate and a GarnP-based layer and a second layer.
FIG. 2 is a cross-sectional view of the basic structure of a light emitting element that emits yellow short wavelength light. IC21: GaP substrate 12.22.32.42: -th layer 13.15.24.33.35.44: Clad layer 14
．． 23.34.43: Active layer 31.41: GaAs substrate E1
, E2: Electrode DR: Diffusion region AR: Light emitting region

Claims (6)

[Claims] (1) A substrate made of a III-V group element, a first layer mainly composed of GaInP formed on the III-V group substrate using a yo-yo solute supply method or a Sn solvent method, and 1. A semiconductor light emitting device comprising: a second layer containing GaInP as a main component formed on the layer using a method selected from MOVPE, MBE, and LPE. (2) The III-V group substrate is made of GaP, and the first layer is yo
The second layer is an AlGaInP cladding layer and a GaInP active layer containing or not containing Al or a GaInP layer formed using a -yo solute supply method.
Claim characterized in that it has a double heterostructure consisting of an nPAs active layer and an AlGaInP cladding layer (
1) The semiconductor light emitting device described above. (3) The III-V group substrate is made of GaP, and the first layer is yo
-yo Consisting of GaInP formed using the solute supply method, with the second layer containing Al or not containing GaI
nP active layer or GaInPAs active layer and AlGaI
2. The semiconductor light emitting device according to claim 1, wherein the semiconductor light emitting device has a single heterostructure comprising an nP cladding layer. (4) The III-V group substrate is made of GaAs, and the first layer is S.
The second layer is made of Sn-doped GaInP formed using an n-solvent method, and the second layer is an AlGaInP cladding layer and a GaInP active layer containing or not containing Al or GaInP.
2. The semiconductor light emitting device according to claim 1, wherein the semiconductor light emitting device has a double heterostructure consisting of an InPAs active layer and an AlGaInP cladding layer. (5) The III-V group substrate is made of GaAs, and the first layer is S.
The second layer is made of Sn-doped GaInP formed using an n-solvent method, and the second layer is made of GaInP that contains or does not contain Al.
InP active layer or GaInPAs active layer and AlGa
2. The semiconductor light emitting device according to claim 1, having a single heterostructure comprising an InP cladding layer. (6) The semiconductor light emitting device according to claim (1), wherein a yo-yo solute supply method is used as LPE for forming the second layer.